Meteorites display an isotopic composition dichotomy between non-carbonaceous (NC) and carbonaceous (CC) groups, indicating that planetesimal formation in the solar protoplanetary disk occurred in two distinct reservoirs. A new model will be introduced to explain this dichotomy from the circumstance that the arrival of the outer CC dust particles in the inner disk is delayed for several million years by the viscous expansion of the protoplanetary disk.
Besides, hydrodynamical modeling has shown that while the Sun's gaseous protoplanetary disk was present, the giant planets migrated into a compact orbital configuration in a chain of resonances. I will show that the giant planets's dynamical instability was likely triggered by the inside-out dispersal of the gaseous disk. Such an instability took place as the disk dissipated, constrained to be a few to ten million years after the birth of the Solar System.